1. Field of the Invention
The present invention relates to a construction of and a method of connecting a connector to a base board, in which the connector can be provided on either side of the circuit board even in the case where solder portions are formed only on one side of the circuit board.
The present application is based on Japanese Patent Application No. Hei. 11-52428, which is incorporated herein by reference.
2. Description of the Related Art
FIG. 6 shows a related construction of connecting a connector to a base board.
In this construction, a plurality of external board-connecting terminals 51 of the board-connecting connector (hereinafter referred to as "connector") 40 are connected respectively to terminal-connecting portions of a printed circuit (not shown) on a front side or surface of an electronic circuit board (hereinafter referred to as "circuit board") 50 by reflow soldering. The connector 40 is mounted on the surface of the circuit board 50 by soldering.
Rows of solder portions 52 are formed on the front side (upper surface) of the circuit board 50, and the rows of board-connecting terminals 51 project outwardly respectively from lower portions of opposite side walls 54 of a connector housing 53 made of a synthetic resin. Each board-connecting terminal 51 is downwardly bent into a crank-shape, and a lower surface of a distal end portion 55 thereof is connected to the upper surface of the circuit board 50 through the solder portion 52.
A flange 56 is formed integrally with a bottom portion of the connector housing 53, and proximal end portions of the board-connecting terminals 51 are disposed on an upper surface of the flange 56. Fixing metal members 60 of an L-shape are provided respectively at opposite end walls 59 of the connector housing 53, and each fixing metal member 60 is engaged in grooves 61, and a lower portion of each fixing metal member 60 is received in a notch 62 in the flange 56, and is fixed at its lower surface to a solder portion 52 on the front side of the circuit board 50. The soldering connection of the board-connecting terminals 51 to the circuit board 50 and the solder-fixing of the fixing metal members 60 are effected simultaneously by a reflow soldering apparatus (described later).
FIGS. 7A to 7D show a related reflow soldering method.
First, as shown in FIGS. 7A and 7B, a sheet 64 of a synthetic resin, having a plurality of holes 63, is placed on the circuit board 50, and a cream solder 65 is put on the sheet 64, and is spread over this sheet, using a knife (not shown). The holes 63 in the sheet 64 are so arranged as to correspond to the relevant solder portions, respectively. The cream solder fills in the holes 63, and deposits on the circuit board 50. Then, the sheet 64 is removed as shown in FIG. 7C, and solder portions 52 are formed on predetermined portions of the circuit board 50, respectively.
Then, the connector 40 is fixedly secured to the solder portions 52 by a thermosetting adhesive (not shown) as shown in FIG. 7D. In this condition, the circuit board 67 with the connector is heated by a reflow soldering apparatus (not shown), and therefore the solder portions 52 are melted, so that the board-connecting terminals 52 (see FIG. 6) of the connector 40 are connected to the circuit board 50 by soldering.
In FIG. 6, when it is desired to provide the connectors 40 on the opposite (front and reverse) sides (surfaces) of the circuit board 50, respectively, solder portions 52 are formed on each side of the circuit board 50 by the above method. By doing so, the two connectors 40 can be connected respectively to mating connectors (not shown) at the opposite sides of the circuit board 50. In the case where such solder portions 52 can not be formed on one side (reverse side) of the circuit board 50, for example, because of the form of the printed circuit on the circuit board 50 and the kind of the reflow soldering apparatus, a connector 41 of the through hole-connecting type is provided on the reverse surface of the circuit board 50 as shown in FIG. 8, board-connecting terminals 68 of the connector 41 are passed respectively through through holes 69 in the circuit board 50, and are connected respectively to solder portions 70 (other than the reflow solder portions) on the front side of the circuit board 50.
In the above construction and method of connecting the connector to the base board, however, in the case where the solder portions 52 can be formed only on one side of the circuit board 50, there are required two steps, that is, the step of connecting the connector 40 to the front side of the circuit board 50 by the reflow soldering apparatus, and the step of subsequently connecting the reverse-side connector 41 to the through holes 69 in the circuit board 50 by soldering. Therefore, the productivity is low, and much time and labor are required for the assembling operation, and particularly when manually soldering the board-connecting terminals 68 to the respective through holes 69, there has been encountered a problem that the efficiency of the operation is extremely low. In the case where the solder portions are formed on the opposite sides (surfaces) of the circuit board 50, there have been encountered problems that the time and labor, twice larger than those required with the method of FIG. 7, are needed and that the operation is cumbersome. In the case where the connectors 40 are connected respectively to the opposite sides of the circuit board 50 by soldering, using the reflow soldering apparatus, the solder portions 52 on the lower side of the circuit board 50 drip, and therefore the soldering connection is difficult, which has resulted in a problem that complicated techniques and the high cost are required. A further problem is that the structure becomes bulky in the direction of the thickness of the circuit board 50 since the connector housing 53 projects from the surface of the circuit board 50 through the flange 56.
With the above problems in view, it is an object of the present invention to provide a construction and a method of connecting a connector to a base board, in which a board-connecting connector can be efficiently provided on either side of the circuit board with less time and labor even in the case where solder portions can be formed only on one side of the circuit board, and the increase of the time and labor due to the formation of solder portions on opposite sides of the circuit board are eliminated, and connectors can be positively and easily connected to the opposite sides of the circuit board, respectively, and the structure is prevented from becoming bulky.
To achieve the above object, according to one aspect of the present invention, there is provided a construction of connecting a connector to a circuit board, which comprises a circuit board having a connector insertion hole formed therethrough, a plurality of solder portions formed on one of opposite sides of the circuit board, and a plurality of board-connecting terminals attached to a connector, the board-connecting terminals being respectively connected to the solder portions, wherein the connector is inserted into the connector insertion hole from the one side of the circuit board, and each of the board-connecting terminals has a solder-connecting surface facing in a direction of insertion of the connector. According to the present invention, it is preferable that the above construction further comprises a plurality of fixing metal members provided on the connector, and each of the fixing metal members having a solder-fixing surface facing in the direction of insertion of the connector.
Further, according to another aspect of the present invention, there is provided a method of connecting a connector to a circuit board. The method comprises the steps of forming a plurality of solder portions on a circuit board, forming a connector insertion hole through the circuit board, inserting a connector having a plurality of board-connecting terminals into the connector insertion hole from one side of the circuit board, so that the connector projects from the other side of the circuit board, and subsequently connecting the board-connecting terminals of the connector respectively to the solder portions at the one side of the circuit board. According to the present invention, it is preferable that the connector has a plurality of fixing metal members, and the above method further comprises a step of securing the fixing metal members fixedly to the one side of the circuit board by soldering simultaneously when the board-connecting terminals are connected to the solder portions, respectively.